Wet runway with a crosswind brings to mind immediately the diagram of the reverse thrust vectors in such conditions, pretty little diagram if I recall.
Did they depart form a field with slushy deposits on the runway? Is it possible the nosewheel steering cables froze inflight in the U/C retracted position and the lowered gear then put a spurious off-centre demand to the NLG steering jacks?
A NG engineer should be able to state whether the cable rigging changes between the lowered and retracted positions.
The steering bypass handle has been known to stick in the partially disconnected position due to lack of lube and a very tight setting of the handle on the spindle. Try it on a number of your fleet during the walkround and report it as a snag, it should spring positively into the "normal" position once the bypass pin is removed.
Just a few thoughts from 9 years on the type, but I wait to be corrected as we're all still learning I hope.
